A watch manager said he feared crews would never be able to put out the Grenfell Tower fire, as he revealed he wanted to "throw on" a suit and help with rescues.
Anthony Peckham, from Islington fire station, was helping record information from 999 calls made by trapped residents in a command unit truck with a direct view of the burning tower.
He could feel heat "radiating from" the building as people became increasingly frustrated that their loved ones had not yet managed to escape, some screaming phrases such as, 'Why aren't you doing anything?'.
In a written statement to the public inquiry into the blaze, he said: "My fear on my arrival at Grenfell Tower was that we were 'never going to put this fire out'. I held that opinion due to the speed of the fire and the fact that the building was already substantially on fire on our arrival.
"On watching it for several hours from the command unit I held the same opinion."
Mr Peckham described how he felt "glued" to his seat as he recorded details of those trapped, including a pregnant woman, children and babies.
These details were being written on a whiteboard in the command unit truck and then passed via a runner and the radio to the bridgehead in the tower where crews were being deployed.
He went on: "I can recall several calls that were duplicated and as time progressed I was fearful that these people were not being rescued. "I could hear background radio information that we were struggling to get to the upper floors.
"I was frustrated at the lack of information coming through regarding rescues, it felt we had no idea of the progress of the rescue and at times from within the command unit it made me wish I could 'throw on' a suit and get in there to help.
"I knew this was just a general firefighter's reaction as my role was important and needed to be done."
Some 72 people died following the fire on June 14 last year.
The inquiry, held at Holborn Bars in central London, is hearing firefighter evidence for a fourth week.